This invention relates to a deflection yoke adapted to fit about a cathode ray tube, and more particularly to a deflection yoke having one deflection coil wound in a toroidal configuration and another deflection coil wound in a saddle-like configuration with the use of a coil frame composed of a core or coil bobbin the front and rear ends of which are provided with a guide having a plurality of circumferentially arrayed finger members which define an annular channel and which are spaced so as to define a plurality of slots having a predetermined width.
Deflection yokes adapted to fit about a cathode ray tube are generally constructed by winding the wires of both a horizontal deflection coil and vertical deflection coil about a deflection core in a toroidial-type configuration, or by winding the wires of both coils along the length of the core in a saddle-type configuration, or alternatively by adopting the saddle configuration for the horizontal deflection coil and the toroidal configuration for the vertical deflection coil.
In the case of the saddle-type deflection coil, a wire is wound at high speed between two metal dies so that accurate positioning of the individual turns is difficult . Thus, coils of a planned precision cannot be obtained and coils of uniform quality cannot be mass-produced. On the other hand, in a case where toroidal coils are wound directly on the deflection core, the wire is likely to become displaced at the positions of the initial and final turns and undergo deformation due to the shape of the core; as a result, predictable magnetic field patterns cannot be obtained.
A deflection yoke which combines both the toroidal and saddle-type deflection coils must be sectioned along a plane perpendicular to the axis of the cathod ray tube; thus, each of the coils lacks symmetry in all four quadrants, thereby increasing cross-talk between coils and making accurate beam deflection impossible. A deflection yoke of this type requires auxiliary deflection means. For example, when a deflection yoke of the above-mentioned type is employed in a color television picture tube an electron beam which has passed through a deflecting magnetic field is dispersed. Hence, three electron beams are converged by means of a convergence yoke. However, as is widely known, if a precise magnet field can be obtained from a deflection yoke fitted about a cathrode ray tube in which three electron guns are arranged in a row, the three electron beams can be converged over all positions of the CRT screen merely by using the deflection yoke alone. Since this demands a deflection yoke which can converge three beams with an extremely small error, the generation of the deflecting magnetic field must satisfy strict conditions. Moreover, a suitable configuration for the deflection yoke itself is difficult to attain by conventional techniques.
In an effort to overcome these problems, there is known in the art a deflection coil in which winding guides each having an annular channel are secured to the front end and rear end of a deflection core, with wire conductors being wound through the channels to form the horizontal and vertical deflection coils both of which have a toroidal configuration. However, in deflection yokes of this type a large number of conductor turns cannot be wound on the core, a drawback which reduces deflection efficiency since a high inductance and DC resistance cannot be obtained. Other disadvantages such as a requirement for a large deflection voltage, a substantial rise in the temperature of the deflection yoke and a sizable leakage of magnetic flux render these deflection yokes undesirable.